Active acoustic and vibration noise canceling in waterproof camera

ABSTRACT

A camera includes one or more microphone pairs. A first microphone (e.g., a main microphone) is ported to the outside of the camera and captures the desired external audio signal, but may also capture undesired vibrational noise. A second microphone has a similar structure to the first microphone, but is not ported to the outside of the camera. Instead, the second microphone is ported into an enclosed cavity (e.g., 1-2 cubic centimeters in volume). The second microphone may pick up the same vibration excitation and internal acoustic noise as the first microphone but very little of the desired external acoustic sounds around the camera. The unwanted noise can then be removed by subtracting the second audio signal from the second microphone from the main audio signal from the main microphone.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/726,320, filed Oct. 5, 2017, which claims the benefit of U.S.Provisional Application No. 62/405,047 filed on Oct. 6, 2016, both ofwhich are incorporated by reference their entirety.

BACKGROUND Field of Art

The disclosure generally relates to audio systems and in particular tocanceling vibration noise in a camera.

Description of Art

In a waterproof camera, a protective membrane may be placed in front ofthe microphone to prevent water from entering the camera. When thecamera moves or external forces are applied to the camera, the membranemay vibrate. The vibrations may be picked up as acoustic noise by themicrophone. Additionally, other vibrating components inside the cameramay generate additional noise that may reach the microphone. This noiseis generally undesirable and may reduce the quality of desired audiosignal.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed embodiments have advantages and features which will bemore readily apparent from the detailed description, the appendedclaims, and the accompanying figures (or drawings). A brief introductionof the figures is below.

FIG. 1 is a block diagram illustrating an example embodiment of an audiosub-system of a camera.

FIG. 2 is an example embodiment of a camera.

FIG. 3 is a flowchart illustrating an example process for processing anaudio signal in a camera.

DETAILED DESCRIPTION

The figures and the following description relate to preferredembodiments by way of illustration only. It should be noted that fromthe following discussion, alternative embodiments of the structures andmethods disclosed herein will be readily recognized as viablealternatives that may be employed without departing from the principlesof what is claimed.

Reference will now be made in detail to several embodiments, examples ofwhich are illustrated in the accompanying figures. It is noted thatwherever practicable similar or like reference numbers may be used inthe figures and may indicate similar or like functionality. The figuresdepict embodiments of the disclosed system (or method) for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles described herein.

Configuration Overview

In an embodiment, a camera includes one or more microphone pairs. Afirst microphone (e.g., a main microphone) is ported to the outside ofthe camera and captures the desired external audio signal, but may alsocapture undesired vibrational noise. A second microphone has a similarstructure to the first microphone, but is not ported to the outside ofthe camera. Instead, the second microphone is ported into an enclosedcavity (e.g., 1-2 cubic centimeters in volume). The second microphonemay pick up the same vibration excitation and internal acoustic noise asthe first microphone but very little of the desired external acousticsounds around the camera. The unwanted noise can then be removed bysubtracting the second audio signal from the second microphone from themain audio signal from the main microphone.

In a particular embodiment, a camera or other audio capture deviceincludes an audio sub-system that includes structures for enabling noisecancellation. A housing has a microphone port comprising an opening. Afirst waterproof membrane spans the opening. A printed circuit board iscoupled to an interior surface of the housing below the microphone port.The printed circuit board comprises a main microphone opening under themicrophone port and a reference microphone opening laterally offset fromthe microphone port. A main microphone is mounted to a bottom surface ofthe printed circuit board below the main microphone opening. The mainmicrophone detects ambient audio and generates a main audio signal. Areference microphone is mounted to a top surface of the printed circuitboard above the reference microphone opening. The reference microphonecaptures a reference audio signal. A second waterproof membrane spansthe reference microphone opening. A reference structure is configuredsuch that a reference cavity exists below the second waterproofmembrane. One or more sealing gaskets isolates the second microphonefrom the microphone port. A processor (e.g., by subtracting thereference audio signal from the main audio signal).

Audio Sub-System Architecture

FIG. 1 illustrates a cross-sectional view of an embodiment of an audiosub-system 102 of a camera 100. The camera 100 comprises a housing 110with an opening 114 (e.g., a main microphone port) in a top surface ofthe housing 110 sealed by a waterproof membrane 112. The waterproofmembrane 112 covers a main microphone (Mic 1)116 that is mounted to abottom surface of an audio printed circuit board (PCB) 118 on anopposite side of the audio PCB 118 from the member 112. The waterproofmembrane 112 prevents water from reaching the main microphone 116 butenables acoustic waves to reach the main microphone 116 so that the mainmicrophone 116 can capture the ambient audio without substantialdistortion. The audio PCB 118 may include additional electronicssupporting the audio sub-system 102 such as an audio processor, memory,storage, and interconnections between the components. The audio PCB 118may include an opening aligned with the opening 114 in the housing 110to enable ambient audio to reach the main microphone 116. In anembodiment, the audio PCB 118 and the attached main microphone 116 areattached to the housing 110 via an elastomer and sealant. A firstacoustical cavity (V1) 120 is formed between the main microphone 116 andthe membrane 112.

A reference microphone (Mic 2) 122 is mounted at a different position onthe audio PCB 118. For example, the reference microphone 122 may bemounted on a top surface of the audio PCB 118 (e.g., on the side facingthe membrane 112) and may also be coupled to an interior surface of thehousing 110. The bottom surface of the audio PCB 118 below the referencemicrophone 122 may attach to a reference structure 124 cantilevered froman interior side surface (e.g., perpendicular to the top surface) of thehousing 110. The reference structure 124 may include a waterproofmembrane 126 below an opening of the PCB audio 118 below the secondmicrophone 122. The waterproof membrane 126 may be substantially similarin material and thickness to the waterproof membrane 112 such that itproduces a similar or vibrational response in response to the same inputstimulus.

In an embodiment, the reference structure 124 is attached to the bottomsurface of the audio PCB 118 via an elastomer and sealant each havingsimilar structural and material characteristics to the elastomer andsealant used to attach the main microphone 116 to the housing 110. Asecond acoustical cavity (V2) 128 is formed between the referencemicrophone 122 and the second membrane 126. This second acousticalcavity 128 may have substantially the same characteristics as the firstacoustical cavity 120 (e.g., similar shape, volume, and acousticcharacteristics). A reference cavity 130 having a volume V3 is alsoformed below the membrane 126 and above the cantilever referencestructure 124. The volume V3 may be dampened by a dampening element 132.

FIG. 1 also illustrates sealing gaskets 134 between the top surface ofthe PCB 118 and the interior surface of the housing 110 on either sideof the opening 114 in order to isolate the first acoustical cavity 120.Similar gaskets 136 may be placed on the sides of the second acousticalcavity 128 to similarly isolate the second acoustical cavity 128. Thegaskets 134, 126 may comprise ring-shaped gaskets with openings thatalign with the main microphone opening and the reference microphoneopening respectively in the PCB 118. The gaskets 134, 126 substantiallyisolate the reference microphone from the opening 114. Furthermore, thegaskets 134, 126 substantially acoustically isolate the first acousticalcavity and the second acoustical cavity.

FIG. 1 further illustrates a main PCB 150. The main PCB 150 may includevarious electronic components that support general functionality suchas, for example, an image sensor, video processor, memory controller, orother supporting components. The main PCB 150 may include variouscomponents 138 (e.g., integrated circuits or other surface mountcomponents) that may generate vibrational forces resulting invibrational noise inside the housing 110. These vibrations may occur inresponse to external forces Fi acting on the housing 110 caused by, forexample, a user handling the camera, a mount attached to the camera thatexerts a force on the camera in response to motion, or other externalforces.

As can be seen from FIG. 1, the reference microphone 122 is isolatedfrom the external audio source that will be captured by the mainmicrophone 116. However, the reference microphone 122 and the mainmicrophone 116 will both pick up similar vibrational noise because therespective microphone 116, 122, acoustical cavities 120, 128, andmembranes 112, 126 are similar positioned and structured. Furthermore,both microphones 116, 122 are affixed to the same PCB 118 and thereforepick up similar vibrations from the PCB 118. The reference cavity 130and the dampening element 132 within it may also be structured in amanner that causes the reference microphone 122 to capture similarvibrational noise (e.g., frequency and amplitude as the main microphone116. Alternatively, the structure of the reference cavity 130 anddampening element 132 can characterize a baseline noise that can enablea signal processor to estimate the vibrational noise that will becaptured by the main microphone 116. The audio signal from the referencemicrophone 122 (or a transformation thereof) can be subtracted from themain audio signal from the main microphone 116 to improve thesignal-to-noise ratio of the audio signal.

FIG. 2 illustrate an embodiment of an example camera 200 that mayinclude the audio sub-system 102. The camera 200 may comprise a housing110 having a camera lens 204 structured on a front surface of thehousing, various indicators on the front of the surface of the housing202 (such as LEDs, a display 206, and the like), various inputmechanisms (such as buttons, switches, and touch-screen mechanisms), andelectronics (e.g., imaging electronics, power electronics, etc.)internal to the housing 202 for capturing images via the camera lensand/or performing other functions. The camera 200 may be configured tocapture images and video, and to store captured images and video forsubsequent display or playback.

The camera 200 can include various indicators, including a display panel206. The camera 200 can also include buttons 210 configured to allow auser of the camera to interact with the camera, to turn the camera on,and to otherwise configure the operating mode of the camera. The camera200 can also include one or more audio sub-systems 102 which may eachhave the structure described above.

FIG. 3 is a flowchart illustrating an example embodiment of a processfor processing an audio signal. A main audio signal captured by the mainmicrophone is received 302 by a processor. A reference audio signalcaptured by the reference microphone is also received 304 at theprocessor. An output audio signal is generated 306 based on the mainaudio signal and the reference audio signal that has reduced vibrationalnoise relative to the main audio signal. For example, the output audiosignal may be generated by subtracting the reference audio signal fromthe main audio signal. Alternatively, a predefined transformation may beapplied to the reference audio signal to generate a transformedreferenced audio signal, and the output audio signal is then generatedby subtracting the transformed referenced audio signal from the mainaudio signal. Here, the transformation may be predetermined based on acharacterization of the noise captured by the reference audio signalrelative to the main audio signal, which may relate to the physicalproperties of the reference cavity 130 and dampening element 132.

In an alternative embodiment, the audio sub-system 102 of FIG. 1, may beintegrated into an audio capture device that is not necessarily acamera. Here, the various components discussed in FIG. 1 may beintegrated with a device housing of the audio capture device in the samemanner that they are integrated into the housing described above.

Additional Configuration Considerations

Throughout this specification, some embodiments have used the expression“coupled” along with its derivatives. The term “coupled” as used hereinis not necessarily limited to two or more elements being in directphysical or electrical contact. Rather, the term “coupled” may alsoencompass two or more elements are not in direct contact with eachother, but yet still co-operate or interact with each other, or arestructured to provide a drainage path between the elements.

Likewise, as used herein, the terms “comprises,” “comprising,”“includes,” “including,” “has,” “having” or any other variation thereof,are intended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus.

In addition, use of the “a” or “an” are employed to describe elementsand components of the embodiments herein. This is done merely forconvenience and to give a general sense of the invention. Thisdescription should be read to include one or at least one and thesingular also includes the plural unless it is obvious that it is meantotherwise.

Finally, as used herein any reference to “one embodiment” or “anembodiment” means that a particular element, feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. The appearances of the phrase “in oneembodiment” in various places in the specification are not necessarilyall referring to the same embodiment.

Upon reading this disclosure, those of skill in the art will appreciatestill additional alternative structural and functional designs asdisclosed from the principles herein. Thus, while particular embodimentsand applications have been illustrated and described, it is to beunderstood that the disclosed embodiments are not limited to the preciseconstruction and components disclosed herein. Various modifications,changes and variations, which will be apparent to those skilled in theart, may be made in the arrangement, operation and details of the methodand apparatus disclosed herein without departing from the spirit andscope defined in the appended claims.

1-20. (cCanceled)
 21. A camera comprising: a housing having a microphoneport comprising an opening in the housing; a first waterproof membranespanning the opening in the housing; a printed circuit board coupled tothe housing, the printed circuit board including a main microphoneopening and a reference microphone opening; a main microphone coupled tothe printed circuit board corresponding to the main microphone opening,the main microphone configured to capture a main audio signal; areference microphone coupled to the printed circuit board correspondingto the reference microphone opening, the reference microphone configuredto capture a reference audio signal; a second waterproof membranespanning the reference microphone opening; one or more sealing gasketsconfigured to isolate the reference microphone from the microphone port;and a processor to generate an output audio signal based on the mainaudio signal and the reference audio signal.
 22. The camera of claim 21,further comprising: a reference structure configured such that areference cavity exists below the second waterproof membrane.
 23. Thecamera of claim 22, wherein the reference structure comprises: adampening element below the reference cavity to dampen vibrationsexperienced by the reference structure.
 24. The camera of claim 22,wherein the one or more sealing gaskets comprise: a first gasket betweenan interior surface of the housing and a top surface of the printedcircuit board, the first gasket having an opening aligned with the mainmicrophone opening; and a second gasket between a bottom surface of theprinted circuit board and a top surface of the reference structure, thesecond gasket having an opening aligned with the reference microphoneopening.
 25. The camera of claim 24, wherein a first acoustical cavityexists in the opening of the first gasket above the main microphone,below the first waterproof membrane, and wherein a second acousticalcavity exists in the opening of the second gasket below the referencemicrophone, above the second waterproof membrane.
 26. The camera ofclaim 25, wherein the first acoustical cavity and the second acousticalcavity each exhibit a substantially same acoustical response tovibrations.
 27. The camera of claim 25, wherein the first acousticalcavity and the second acoustical cavity have approximately a samevolume.
 28. The camera of claim 22, wherein the reference structurecomprises: a cantilever structure coupled to an interior side face ofthe housing perpendicular to a top face including the microphone port.29. The camera of claim 21, wherein the processor is configured togenerate the output audio signal by subtracting the reference audiosignal from the main audio signal.
 30. The camera of claim 21, whereinthe processor is configured to generate the output audio signal byapplying a transformation to the reference audio signal to generate atransformed reference audio signal and subtracting the transformedreference audio signal from the main audio signal.
 31. An audio devicecomprising: a housing; a first waterproof membrane spanning a port inthe housing; a first structure coupled to an interior surface of thehousing, the first structure including a first microphone opening and asecond microphone opening; a first microphone, the first microphonecorresponding to the first microphone opening and configured to generatea first audio signal; a second microphone, the second microphonecorresponding to the second microphone opening and configured togenerate a second audio signal; a second waterproof membrane spanningthe second microphone opening; a gasket configured to separate thesecond microphone from the port; and a processor configured to generatean output audio signal based on the first audio signal and the secondaudio signal.
 32. The audio device of claim 31, wherein the gasketcomprises: a first gasket between the housing and the first structure,the first gasket having a first gasket opening aligned with the firstmicrophone opening; and a second gasket between the first structure anda second structure, the second gasket having a second gasket openingaligned with the second microphone opening.
 33. The audio device ofclaim 32, wherein a first acoustical cavity exists in the first gasketopening below the first waterproof membrane, and wherein a secondacoustical cavity exists in the second gasket opening above the secondwaterproof membrane.
 34. The audio device of claim 33, wherein the firstacoustical cavity and the second acoustical cavity each exhibit asubstantially same acoustical response to vibrations.
 35. The audiodevice of claim 33, wherein the first acoustical cavity and the secondacoustical cavity have approximately a same volume.
 36. The audio deviceof claim 31, wherein the processor is configured to generate the outputaudio signal by subtracting the second audio signal from the first audiosignal.
 37. The audio device of claim 31, wherein the processor isconfigured to generate the output audio signal by applying atransformation to the second audio signal to generate a transformedaudio signal and subtracting the transformed audio signal from the firstaudio signal.
 38. A system comprising: a first microphone configured togenerate a first audio signal; a first waterproof membrane configured towaterproof the first microphone; a second microphone configured togenerate a second audio signal; a second waterproof membrane configuredto waterproof the second microphone; a gasket configured to separate thesecond microphone from the first microphone; and a processor configuredto generate an output audio signal based on the first audio signal andthe second audio signal.
 39. The system of claim 38, further comprising:a structure configured such that a cavity exists below the secondwaterproof membrane.
 40. The system of claim 39, wherein the structurecomprises: a dampening element below the cavity to dampen vibrationsexperienced by the structure.